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Researchers Pursue Seemingly Rare HIV Strain

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WEDNESDAY, Feb. 16 (HealthDay News) -- Following reports last week of the possible emergence of a potentially more aggressive form of the virus that causes AIDS, researchers continue to perform tests that should reveal the true nature of the HIV strain that infected a New York City man.

It's possible the unidentified man was especially vulnerable to HIV. But if he turns out to have a normal immune system, that could mean his body is now home to an especially powerful and drug-resistant strain of AIDS -- and one that may already have spread to other people, experts said.

On Monday, health officials in San Diego announced they were looking for a man recently diagnosed with HIV who appears to harbor a strain similar to that found in the New York man. It's not clear if the two men are connected in any way.

Many AIDS specialists believe the headline-grabbing case of the New York patient will result in findings indicating something about his immune system left him vulnerable to quick infection by a rather ordinary strain of HIV. The other alternative -- a new, drug-resistant strain of HIV -- is "quite scary," said Dr. Joseph Baran, an AIDS specialist at Scripps Mercy Hospital in Chula Vista, Calif.

While the New York man's identity is being withheld, local health officials did release a few facts about him on Feb. 11, when they announced initial details about his case. He's in his mid-40s, he used the street drug crystal methamphetamine, and he had unprotected anal sex with multiple male partners. Tests suggest -- but don't confirm -- that he was infected with HIV in October and then diagnosed with full-blown AIDS within months.

Typically, it takes an average of about 10 years for someone to be stricken with AIDS after infection with HIV. In the New York City man's case, full-blown AIDS appeared in a matter of weeks, not years. What makes the man's case even more exceptional is that he's also resistant to virtually all of the antiviral AIDS drugs that combat the disease.

"To go from infection to disease in a matter of a few months is very unusual. To do that in conjunction with such a highly resistant strain is also unusual," New York City Health Commissioner Thomas R. Frieden said last Friday. "Putting them both together is what's so unique."

If the man had simply fallen ill with AIDS quickly, he would have been one of the estimated 40,000 people who become HIV-positive in the United States each year. But tests revealed that the virus in his body is resistant to 19 of 20 available AIDS drugs, meaning his strain is both quick-acting and extremely difficult to treat, experts said.

The man appears to fall into the 1 percent of HIV patients whose immune system promptly falls apart after they're infected, said Dr. Bob Shafer, assistant professor of medicine at Stanford University.

A new round of tests should provide more information about the man's own susceptibility. Some of those tests are being carried out by Dr. David Ho, who heads the Aaron Diamond AIDS Research Center in Manhattan, which is handling some of the studies in conjunction with the New York Health Department, The New York Times reported. While some findings may be available in a week, others will take longer, said Ho, who in the 1990s pioneered the development of HIV-suppressing combination drug therapies that have extended the lives of many patients.

Dr. Robert Siliciano, an AIDS specialist and professor of medicine at Johns Hopkins University, said, "It's possible that the way the virus interacted with [the patient's] immune system was particularly unfavorable. In another person, that same virus may have taken a lot longer to produce immunodeficiency."

Then there's the possibility that there's nothing unique about the man, that the strain itself is extremely unusual. "The worst-case scenario is that the virus is highly pathogenic in everybody," Siliciano said. "That really hasn't been described before, and you'd need to have more cases in order to say that was actually occurring."

More information

To learn more about HIV/AIDS prevention, visit the U.S. Centers for Disease Control and Prevention.

SOURCES: Joseph Baran, M.D., AIDS specialist, Scripps Mercy Hospital, Chula Vista, Calif.; Bob Shafer, M.D., assistant professor of medicine, Stanford University, Palo Alto, Calif.; Robert Siliciano, M.D., professor of medicine, Johns Hopkins University, Baltimore
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